I agree with others that a travel trailer fits your budget. You can get it towed to your Pittsburgh residence, and then look at getting a truck for it when you retire and are ready to travel, or use it as a trade in towards that motorhome.
I have an 18 ft Shasta travel trailer. It has plenty of room for one, and is a good size for two people. It was 10k and purchased new.
I use it year-round in the side yard - it is plugged into a 30 amp setup at the house.
I winterize in November, and don't even think about running water through it until April. (That is something else to consider about any RV you might get - in winter Pittsburgh weather means freezing weather.)
I use gallon jugs of water to wash hands using a basin - I just toss the water into the garden. I keep a sickroom style bedside commode in the bathroom with a plastic liner and kitty litter in the commode part. Not perfect, but it works without water if someone is spending the night in the trailer and does not want to come in the house in the middle of the night to use the bathroom.
I have an electric heater in the TT, but the cold still comes in through the windows. I need to cover the windows here in WV to keep the warmth in, and she likely will need to do the same in Pittsburgh. (I use silver windshield screens.)
Good luck to you.